text: Thermal additions of stannanes are limited (because of the high temperatures and pressures required) to only simple aldehyde substrates. Lewis acid promoted and transmetalation reactions are much milder and have achieved synthetic utility. Intramolecular addition gives five- or six-membered rings under Lewis acidic or thermal conditions.
  The possibility of incorporating oxygen-containing substituents into allyl- and allenylstannanes expands their scope and utility substantially over methods relying on more reactive organometallics. These compounds are usually prepared by enantioselective reduction with a chiral reducing agent such as BINAL-H. In the presence of a Lewis acid, isomerization of α-alkoxy allylstannanes to the corresponding γ-alkoxy isomers takes place.
  The use of chiral electrophiles is common and can provide "double diastereoselection" if the stannane is also chiral. Chelation control using Lewis acids such as magnesium bromide can lead to high stereoselectivities for reactions of α-alkoxy aldehydes.
  Nucleophilic addition to propargyl mesylates or tosylates is used to form allenylstannanes. These compounds react similarly to allylstannanes to afford homopropargyl alcohols, and any of the three reaction modes described above can be used with this class of reagents as well.
  Imines are less reactive than the corresponding aldehydes, but palladium catalysis can be used to facilitate addition into imines. The use of iminium ions as electrophiles has also been reported.